1. Field of the Invention
The present invention relates to a process for dimerization of a lower .alpha.-olefin. More particularly, the present invention relates to a process for dimerization of a lower .alpha.-olefin which uses a novel nickel-containing Ziegler catalyst.
2. Description of the Related Art
Dimers of lower .alpha.-olefins such as ethylene, propylene, butene, etc., are useful as basic compounds in the production of agricultural chemicals, perfumes and other chemicals or as monomers for the production of polymers. Some of the known processes for the preparation of the dimers of lower .alpha.-olefin comprise dimerization of the -olefin in the presence of a nickel-containing Ziegler catalyst.
For example, Japanese Patent Kokai Publication No. 167932/1982 discloses a catalyst comprising a nickel salt, a trialkylaluminum, an organic phosphine, a halogenated phenol and water. When the .alpha.-olefin is dimerized in the presence of such a catalyst, in some cases, a small amount of precipitates may be formed in the reaction system, which results in reduction of cooling efficiency of a heat exchanger for cooling the reaction system.
It was proposed to use a catalyst comprising a nickel salt of an organic acid, a trialkylaluminum, an organic phosphine and fluorinated isopropanol (cf. Japanese Patent Kokai Publication No. 158225/1987).